April 22 marks the anniversary of the first Earth day in 1970. A senator from Wisconsin decided to organize a demonstration across the country to bring awareness to the problem of pollution, and every year since it has been celebrated as Earth Day. The day is an opportunity to spread awareness, organize a clean up, or educate yourself about our impact on the planet. Learn how to be a planet hero with National Geographic or check out one of the books below to learn more about celebrating our Earth or to discover environmentalists who are leading the way to make positive change.